Investigation of E-Turbo Fuel Consumption Reduction Implications on Passenger Car Applications

none3One of the main challenges related to the development of modern propulsion systems for light duty vehicles is the reduction of CO2 emissions, which may be achieved through different approaches. If we consider the Spark Ignition (SI) Internal Combustion Engine (ICE), relatively high efficient solutions have been recently developed by drastically reducing engine displacement, while at the same time guaranteeing adequate driving performance by adding turbocharging systems and/or additional energy storage and propulsion systems (hybrid powertrains. [1]). Exhaust energy waste is certainly another extremely interesting area for increasing the overall efficiency of the powertrain [2-4], and it should be recalled that the combination of exhaust gas turbocharging with energy recovery through turbo machines is a wellestablished technology for large engines (turbo-compound [3, 7, 8, 9]), while it is recently being considered also for highly downsized engines, due to more frequent operation at high load [6]. This paper investigates a possible approach for extreme CO2 reduction, consisting of an E-turbo concept (a reversible electrical machine mechanically coupled to an exhaust gas turbocharger) applied to a “small” 1.4 liter SI engine. The hybridization technology that has been considered in this study is similar to the F1 2014 ERS (Energy Recovery System) system, but the main focus is on fuel consumption reduction evaluation when considering a passenger car application. The simulation analysis has been carried out by defining a reference, fully validated, turbo-charged engine model, and by subsequently investigating required turbine boundary conditions (mainly backpressure and efficiency), both for a Waste Gate (WG) and a Variable Geometry Turbine (VGT) solution. This preliminary analysis allowed the definition of a suitable turbocharger matching for the E-turbo configuration, and the capability of analyzing particularly interesting phenomena, such as part load lower bounds (limits of energy recovery definition), achievable level of downsizing and downspeeding (by investigating different transmission ratios), and the transient response of the E-Turbo system. This simulation environment will be used in the next steps of the project [11] to evaluate the effects of E-turbo concepts (and related downsizing/downspeeding benefits) on fuel consumption, when considering homologation cycle scenarios. Another area to be deeply investigated is the definition of the electric machine performance requirements.noneBaldrati A; Cavina N; Pini NBaldrati A; Cavina N; Pini